Methods to mobilize progenitor andor stem cells from the bone marrow to the bloodstream by administering a combination of at least one CXCR4 inhibitor, at least one CXCR2 agonist, and G-CSF are described. Each heat exchanger coil includes a large section of tubing in which are disposed four smaller sections of tubing. A first etching is performed to the mask composite layer, using the first tri-layer photoresist as a mask, to form at least one first opening in an upper portion of the mask composite layer.